Regulation of Nox Enzymes by Calcium and Novel Subunits

描述（由申请人提供）：Nox/Duox酶-产生超氧化物和次级活性氧（ROS）的nadph氧化酶-参与正常生理，包括细胞信号传导，先天免疫，甲状腺激素合成和重力感知。这些酶产生的ROS与分子损伤和异常信号有关，这些疾病包括：增生性疾病（如癌症、高血压、动脉粥样硬化）、纤维化疾病（肺纤维化、肝硬化、糖尿病肾病）、炎症性疾病（ARDS、关节炎、动脉粥样硬化）和再灌注损伤（中风、心肌梗死、器官移植）。七种人体Nox同工酶反映了三种调节模式：1)组成活性（Nox4）；2)通过与调控亚基（Nox1、Nox2和Nox3）的组装激活；3)钙活化（Nox5， Duox1和Duox2）。我们将研究催化亚基调控的分子机制，以Nox2作为亚基调控Nox的代表，Nox4作为本构活性Nox的代表，Nox5作为Ca2+调控的Nox。有待探讨的潜在假设是，所有三种激活机制在催化部分诱导相同的活性构象，允许电子从NADPH流动形成ROS。催化亚基上与钙或亚基反应有关的区域将被识别和表征，信息将使用新开发的Nox催化亚基同源结构模型进行整合。我们将探索催化必需二聚化的可能性，并将通过对多个物种中100多种Nox酶的进化比较来研究关键保守蛋白区域的作用。对Nox/Duox酶调控的分子理解将提供关键信息，这将是防止过量或不适当的ROS生成和减轻这些疾病进程的关键。

DESCRIPTION (provided by applicant): Nox/Duox enzymes - NADPH-oxidases that generate superoxide and secondary reactive oxygen species (ROS) - participate in normal physiology including cell signaling, innate immunity, thyroid hormone synthesis, and gravity perception. Over-production of ROS by these enzymes is associated with molecular damage and aberrant signaling in disease classes such as hyperproliferative disorders (e.g., cancer, hypertension, atherosclerosis), fibrotic disease (pulmonary fibrosis, cirrhosis, diabetic nephropathy), inflammatory disorders (ARDS, arthritis, atherosclerosis), and reperfusion injury (stroke, myocardial infarction, organ transplantation). The seven human Nox isoenzymes reflect three modes of regulation: 1) constitutively active (Nox4); 2) activation by assembly with regulatory subunits (Nox1, Nox2 and Nox3); and 3) calcium-activated (Nox5, Duox1 and Duox2). We will study the molecular mechanisms of regulation of the catalytic subunits, using Nox2 as representative of subunit-regulated Noxes, Nox4 as a constitutively active Nox, and Nox5 as a Ca2+regulated Nox. The underlying hypothesis to be explored is that all three activation mechanisms induce the same active conformation in the catalytic moiety, allowing electron flow from NADPH to form ROS. Regions on the catalytic subunit involved in responding to calcium or subunits will be identified and characterized, and information will be integrated using a newly developed homology structural model of the Nox catalytic subunit. We will explore the possibility of catalytically essential dimerization, and will investigate the roles of key conserved protein regions identified by an evolutionary comparison of more than 100 Nox enzymes in multiple species. A molecular understanding of the regulation of Nox/Duox enzymes will provide key information that will be key to preventing excess or inappropriate ROS generation and mitigating the course of these diseases.